1. Field of the Invention
This invention relates to a noncontact power-transmission coil for use in power transmission in a noncontact manner using electromagnetic induction, when charging a rechargeable battery incorporated in a small-size, thin portable terminal such as a mobile phone unit. The invention further relates to a portable terminal and terminal charging device incorporating such a noncontact power-transmission coil, and to a magnetic layer formation device and magnetic layer formation method for forming a magnetic layer in a planar coil of such a noncontact power-transmission coil.
2. Description of the Related Art
In the past, systems have been known in which charging power to charge a rechargeable battery incorporated within a portable terminal, for example, has been transmitted by electromagnetic induction using a noncontact power-transmission coil.
In addition, Japanese Unexamined Patent Application Publication No. 2006-42519 (FIG. 2 and FIG. 3) discloses a planar coil as a noncontact power-transmission coil mounted on a portable terminal desired to be thin, such as a mobile phone unit. In this case, the planar coil is constructed such that an electric wire is formed of a single or twisted wire. The surface of the wire is provided with an insulating layer. In addition, the wire is spirally wound in a substantially same plane. Furthermore, this Patent Document also discloses that the formation of a magnetic sheet. That is, a planer coil on the power-transmitting side and a planar coil on the power-receiving side are arranged facing to each other. Then, the counter surface of each coil, which is opposite to the surface facing to the other coil, is entirely covered with a magnetic sheet to prevent undesired radiation with the magnetic field generated from both coils.